Contrary to popular belief, a no sew ring sling does still require the edges of your fabric to be hemmed. If you don't own a sewing machine, this can be done by hand or by a local dry cleaners.

Then, using a pair of large sling rings, follow these instructions for an easy no-sew ring sling. Alternatively, instead if folding the fabric through both rings, you can thread the top like you would the bottom like this. This is a good option if you plan to leave it permanently threaded as a ring sling for regular use. Both methods are equally safe, however. The tension of baby's weight is what keeps the fabric from sliding through the rings.